(1) Field of the Invention
This invention relates to glycopeptide antibiotics represented by the following formula I: ##STR3## wherein R is ##STR4## or H, wherein X is NH.sub.2 and Y is CH.sub.3 ; or X is OH and Y is H, and its pharmaceutically acceptable salt. This invention further relates to their production and microorganisms producing them.
(2) Description of the Prior Art
Recently, as a lot of antibiotics have generally been used, the emergence of the microorganism resistant against many kinds of antibiotics, especially methicillin-resistant microorganism, has been growing into a severe problem. The methicillin-resistant microorganism is resistant not only against methicillin but also against almost all of antibiotics such as aminoglycosides, tetracyclines, cephalosporins, cephamycins, penems, carbapenems and macrolides.
It has been discovered that glycopeptides, especially vancomycins, show potent activity against said methicillin-resistant microorganisms (Antimicrobial Agents and Chemotherapy 28, 660-662 (1985)). Vancomycin is a well-known antibiotic (Japanese Patent Publication No. 33-8450) and its new analogs have been discovered (Antimicrobial Agents and Chemotherapy 28, 660-662 (1985); The Journal of Antibiotics 37, 446-453 (1984), 38, 1-8 (1985), 38, 51-57 (1985); Japanese Unexamined Patent Publication Nos. 60-39623, 60-199397, 60-231698, 60-237099, and so on). Antibiotics PA-42867-A and PA-42867-B of this invention are new vancomycin antibiotics having different structures from those of the above-mentioned compounds.
Vancomycin now on the market which has low purity has been used as orally administrable preparations and is difficult to apply as injectable preparations. Accordingly, it is desired to explore such an antibiotic having more potent activity against methicillin-resistant microorganisms than conventional Vancomycins.